Magnetic catch



Dec. 3, 1957 M. c. 'rr-:EToR 2,815,235

MAGNETIC CATCH Filled Aug. 4, 1953 United States MAGNETIC CATCH Macy O. Teetor, New Orleans, La.

Application August 4, 1953, Serial No. 372,227

Claims. (Cl. 292-2515) This invention relates to a novel magnetic catch for use on doors or the like and more particularly to a heavy duty magnetic catch adapted for use on large or heavy doors.

Heretofore in the art numerous suggestions have been made for utilizing magnetic principles in catches and retaining devices for use on doors or other closure members. However, for the most part the magnetic catches previously proposed have not been suitable for use on large or heavy doors which require a relatively powerful permanent magnet element. When a powerful permanent magnet element is employed in a magnetic door catch, the magnetic forces holding the door in closed or open position are frequently so great that the door cannot be moved with normal eifort. Consequently, for satisfactory operation of a heavy duty magnetic door catch special provision must be made to facilitate disruption of the magnetic attractive forces holding the door in fixed position in order to permit easy opening or closing of the same. As will hereinafter appear, the present invention solves this problem by utilizing in a magnetic catch a novel armature construction which cooperates in a unique manner with a powerful magnet unit.

Accordingly, one object of the present invention is to provide a novel magnetic catch which is particularly adapted for heavy duty use, e. g. with large or heavy doors or the like.

Another object of the invention is to provide a novel magnetic door catch utilizing a powerful permanent magnet for holding heavy doors or the like in closed or open position.

A further object of the invention is to provide novel means for utilizing a powerful permanent magnet in a magnetic door catch while at the same time permitting opening or closing of the door with normal effort.

An additional object of the invention is to provide a novel magnetic catch for doors or the like characterized by a novel armature construction which is particularly adapted to cooperate with a powerful or heavy duty magnet unit.

Other objects and advantages of the invention will become apparent from the subsequent detailed description ltaken in conjunction with the accompanying drawing, wherein:

Fig. 1 is a fragmentary front elevational view of the upper outer corner of a door frame and door assembly with the door in closed position and with a magnetic catch comprising one specific embodiment of the invention mounted thereon;

Fig. 2 is a vertical sectional view taken along the line 2-2 of Fig. 1;

Fig. 3 is a vertical sectional view taken along the line 3-3 of Fig. 2;

Fig. 4 is a view similar to Fig. 2 but showing the door in the process of being opened; and

Fig. 5 is a bottom view as seen looking upwardly along the line 5-.5 of Fig. 2.

Referring to the drawing, the'invention is illustrated f in connection with a door 11 which is mounted for swinging movement by hinges (not shown) on a door frame comprising a horizontal top or cross portion 12, a Vertical side portion 13, and outermost front and rear facing boards 14 and 16. A door stop or jamb 17 extends around the inside of the door frame and is rigidly secured thereto in recessed relation from the front thereof, the door 11 being adapted to abut the jamb 17 in the usual manner when closed.

A magnetic catch comprising one specific embodiment of the present invention is mounted on the door and frame assembly and consists of a powerful permanent magnet unit, indicated generally at 1S, and a cooperating armature unit, indicated generally at 19. As will hereinafter appear, the magnet unit 18 and the armature unit 19 are mounted in coacting positions on the door and frame members with the magnet unit in this instance being mounted at the top of the door frame and the armature unit being mounted on the door. However, it is also within the scope of my invention to reverse the respective mountings of the magnet and armature units so that the magnet unit is located on the door and the armature unit is attached to the door frame. Also, the catch may be mounted at the side or bottom of the door and frame assembly.

Referring now particularly to Figs. 2, 3, and 5, the magnet unit 18 comprises an upright generally tubular permanent magnet element 21 having a flattened or substantially oval cross-sectional configuration (Fig. 5). The magnet element 21 is preferably magnetized so as to have a positive pole at one axial end thereof and a negative pole at the opposite end thereof. For purposes of the present invention, the permanent magnet element 21 is preferably a rather powerful type such as a 50 pound magnet. The structure of the magnet unit 13 also includes a pair of elongated laterally extending upper and lower pole pieces 22 and 23, respectively. The pole pieces 22 and 23 are rigidly secured at the opposite poles of the magnet element 21 by means of a pair of elongated screws 24 which extend through suitable apertures in the pole pieces and through the hollow interior of the magnet element 21. The head portions of the screws 24 are recessed within the upper pole piece 22, as at 26, and suitable nuts 27 or other fasteners are affixed to the protruding lower ends of the screws 24 below the pole piece 23 for rigidly clamping the magnet and its pole pieces together as a unit.

The lower pole piece 23 is a flat elongated metal plate which projects forwardly and rearwardly from the magnet element 21. The upper pole piece 22 is also an elongated metal plate having a central attaching portion with a plurality of apertures 28 permitting the magnet unit 18 to be rigidly mounted at the underside of the cross member 12 of the door frame by means of a plurality of screws 29 extending upwardly through the apertures 28 into the door frame. The lower pole piece 23 is provided with a plurality of complementary enlarged apertures 21 aligned with the apertures 28 to facilitate mounting of the assembled magnet unit 18, the holes 31 permitting a screwdriver or other tool to be inserted therethrough for manipulating the fastening screws 29. The forward end portion of the upper polepiece 22 is bent downwardly and thence outwardly in an off-set manner, as at 32, in order to be positioned more closely adjacent the corresponding end of the pole piece 23 and also to clear the door stop or jamb 17 which is usually too light or weak to permit mounting of the magnet unit thereon. The rear end portion of the upper pole piece 22 is bent downwardly, as at 33, and terminates a short distance from the corresponding rear end of the lower pole piece 23 so as to provide a leakage gap 34 therebetween. It will readily beunderstood bythose familiar with magnetic principles that the leakage gap 34 is correlated with the other design characteristics of the magnet unit to provide the desired flux leakage when the armature unit is not connected across the poles of the magnet unit.

Any suitable magnetic metal or alloy may be used for the permanent magnet element 21, but the alloy of aluminum, nickel and cobalt commercially known as Alnico is particularly suitable. The pole pieces 22 and 23 are made from a metal such as steel having a high degree of magnetic permeability so as to constitute in effect extensions of the poles of the magnet element.

From Figs. l and 2 in particular, it will be seen that the end faces, indicated at 36 and 37, of the parallel forward end portions of the pole pieces 22 and 23, respectively, constitute the effective contact surfaces of the magnet unit and are disposed in recessed or rearwardly spaced relation from the inside surface of the door 11 for coaction with the armature unit 19. The armature unit 19 comprises an elongated armature support extending rigidly from the door 11 and in this instance in the form of an elongated screw or bolt 38 of brass or other nonmagnetic metal. The bolt 38 extends inwardly through the door 11 and has mounted thereon at the inside of the door a short tube 39 with a pair of washers or retainers 41 and 42 at the opposite ends thereof and a nut 43 secured tightly on the end of the bolt 38 for clamping the entire assembly together in a rigid manner, as will be clearly understood from Fig. 2. Of course, the tube 39, the washers 41 and 42 and the nut 43 are also of brass or other non-magnetic metal.

An armature element in the form of a disk 44 of steel or other magnetic metal or alloy is loosely carried in slidable relation on the tube 39, the disk 44 having a central aperture 46 which is slightly larger than the external diameter of the tube 39 so as to permit relative sliding movement therebetween. The armature unit 19 is completed by a pair of helical or spiral springs 47 and 4S which are disposed around the tube 39 on opposite sides of the armature disk 44 for the purposes hereinafter described. Thus, the spring 47 coacts between the armature disk 44 and the retaining washer 41 at the outermost end of the armature support, and the spring 48 coacts between the armature disk 44 and the innermost retaining washer 42 which abuts the inner surface of the door 11. It will readily be seen that in the normal disengaged position of the armature unit, the disk 44 will be held in a more or less centrally disposed position on the tube 39 by means of the oppositely acting spring members 47 and 48.

When the door 11 is in closed position, as seen in Fig. 2, the free outer end of the armature support projects between the operating end portions of the pole pieces 22 and 23, and the armature disk 44 is thus brought into direct surface contact with the contact faces 36 and 37 of the magnet pole pieces. In this position of the device, the spring 47 is preferably under slight compression so that the door 11 is in effect held in closed position under the pressure exerted by the spring 47 which coacts between the armature 44 and the retaining means at the outer end of the armature support, By reason of the enlarged central aperture 46 and the provision of the spring 47, it will be understood that the armature disk 44 can undergo a certain degree of angular or cocking movement relative to the tube 39 so as to permit alignment and full surface contact with the effective faces 36 and 37 of the magnet pole pieces. Accordingly, the construction of the armature unit is such as to compensate for slight irregularities or errors in the mounting of the device and also for misalignment caused by warping, sagging, and other distortion of the door and frame members. Of course, it is important that the end extremities of the magnet pole pieces, i. e. the end faces 36 and 37, be properly aligned so as to permit full atwise contact with the coacting contact face of the armature disk 44.

As hereinbefore mentioned, the magnetic catch comprising the present invention is particularly designed for heavy duty usage and the permanent magnet element 21 is preferably of a relatively powerful type. Under these conditions, it will be appreciated that when the door 11 is in closed position, as in Fig. 2, the armature element 44 is held against the magnet unit with great force such that disruption of the magnetic engagement would be extremely diflicult to accomplish solely by human effort. However, the slidable relationship between the armature support and the armature element 44 as above described, makes it possible to utilize the inertia of the relatively heavy door 11 to assist in breaking the magnetic contact. In Fig. 4 the device is shown with the door 11 in the process of being opened and it will be seen that because of the sliding or movable relationship of the tube 39 relative to the disk 44, the door 11 can be pulled outwardly to the limited degree indicated in Fig. 4 without opposing the strong magnetic bond between the armature and magnet units. During this slight degree of limited outward movement, the user merely exerts sufficient pull on the door to overcome the force of the spring 47 so that the latter is ultimately completely collapsed between the retaining washer 41 and the disk 44 as shown in Fig. 4. However, at this point the inertia of the outwardly moving door 11 supplements the pull or force exerted by the user on the door and disruption of the magnetic contact between the armature disk 44 and the magnet pole pieces is readily effected. Of course, it will be realized that when the spring 47 is completely collapsed, as in Fig. 4, a substantially rigid connection is thereby provided between the bolt 38 and the disk 44 so that the full inertia of the moving door 11 is transmitted directly against the armature disk 44.

Although not illustrated in the drawing, when the magnetic contact is completely disrupted or broken as described above, the released armature disk 44 will obviously be forced along the tube 39 toward the door 11 under the pressure of the compressed or collapsed spring 47. In order to avoid severe impact and noise, the spring 48 is interposed as a cushion or resilient buffer to prevent the disk 44 from being projected against the door 11. Obviously, any other suitable cushioning means could be utilized to prevent this noisy and undesirable impact.

Although the invention has been described with particular reference to a certain specic structural embodiment, it is to be understood that various modifications and equivalent structures may be resorted to without departing from the scope of the invention as defined in the appended claims.

I claim:

l. In a magnetic catch for holding a closure member in fixed position adjacent a frame member, the combination of an elongated armature support adapted to be rigidly mounted on one of said members, an armature element carried on said support for movement longitudinally therealong and adapted to engage a permanent magnet unit on the other of said members for holding the closure member in fixed position, resilient means coacting between said support and said armature element for holding the closure member in xed position under resilient pressure, the slidable relation between said support and said armature element permitting limited outward movement of said support relative to said armature element in response to movement of said closure member from said fixed position whereby the inertia of the moving closure member causes disruption of the magnetic engagement between the magnet unit and said armature element, and cushioning means adapted to coact between said armature element and said one member to prevent severe impact of the armature element against said one member under the pressure of said resilient means when said magnetic engagement is disrupted.

2. The device of claim 1 further characterized in that said resilient means and said cushioning means comprise oppositely acting spring means.

3. In a magnetic catch for holding a closure member in lixed position adjacent a frame member, the com` bination of an elongated support adapted to extend rigidly from one of said members, an apertured armature element slidably mounted on said support with the support extending therethrough, said armature element being adapted to engage a permanent magnet unit on the other of said members for holding the closure member in fixed position, retaining means at the outermost end of said support, and a pair of spiral springs around said support, one of said springs being operatively interposed between said retaining means and said armature element and the other of said springs being operatively engaged with said armature element and adapted to coact with said one member, said one spring thereby being adapted to retain the closure member in fixed position under spring pressure and also being compressible to permit limited outward .movement of said support relative to said armature element in response to movement of said closure member from said fixed position whereby the inertia of the moving closure member facilitates disruption of the magnetic engagement between the magnet unit and said armature element when said one spring is collapsed, and said other spring being adapted to cushion said armature element to prevent impact thereof against said one member under the pressure of said one spring when said magnetic engagement is disrupted.

4. In a magnetic catch for holding a closure member in tixed position adjacent a frame member, the combination of an elongated armature support adapted to be rigidly mounted on one of said members and to extend between the spaced pole pieces of a magnet unit on the other of said members when said closure member is in fixed position, a generally disk-shaped armature element slidably mounted on said support and adapted to engage the ends of said pole pieces for holding the closure member in fixed position, a spiral spring coacting between said armature disk and the outermost end of said support for holding the closure member in iixed position under spring pressure, the slidable relation between said support and said armature disk permitting limited outward movement of said support relative to said disk and against the action of said spring in response to outward movement of said closure member from fixed position whereby the inertia of said moving closure member facilitates disruption of the magnetic engagement between said armature disk and said pole pieces when said spring is fully collapsed, and cushioning means adapted to coact between said armature disk and said one member to prevent severe impact of the armature disk against said one member under the pressure of said spring when said magnetic engagement is disrupted.

5. In a magnetic catch for holding a closure member in fixed position adjacent a frame member, an armature unit comprising an elongated support adapted to extend rigidly from one of said members and to project between the pole pieces of a magnet unit mounted on the other of said members, an armature element slidably mounted on said elongated support and adapted to engage said pole pieces for holding the closure member in xed position, retaining means at the outermost end of said support, and a spiral spring surrounding said support and coacting between said retaining means and said armature element whereby said closure member is retained in fixed position under spring pressure, the slidable relation between said support and said armature element permitting limited outward movement of the support relative to the armature element in response to outward movement of said closure member and against the action of said spring whereby the inertia of the moving closure member facilitates disruption of the magnetic engagement between said armature element and the pole pieces of the magnet unit when said spring is fully collapsed.

6. The device of claim 5 further characterized in that a second spiral spring is mounted on said support on the opposite side of said armature element and adapted to coact between said armature element and said one member for cushioning the movement of said armature element when the latter is released from the magnet unit under the pressure of said irst named spring.

7. In combination, a supporting closure or frame member and an armature unit mounted on said member for coaction with a magnet unit on an adjacent supporting member whereby to permit the closure member to be retained in fixed position adjacent the frame member when said armature unit is in magnetic engagement with the magnet unit, said armature unit comprising an elongated support extending rigidly from said member, an armature element loosely mounted on said support in slidable relation therewith and adapted to engage the permanent magnet unit when the closure member is in said xed position, retaining means at the outer end of said support, a spiral spring around said support and coacting between said retaining means and said armature element, said support being adapted to undergo limited movement relative to said armature element in response to outward movement of said closure member when the armature element is in magnetic engagement with the magnet unit whereby the inertia of the moving closure member facilitates disruption of said magnetic engagement when said spring is fully collapsed, and cushioning means interposed between said armature element and said member for cushioning the impact of said armature element against said member when said armature element is released from the magnet unit under the pressure of the collapsed spring.

8. A magnetic catch for holding a closure member in xed position adjacent a frame member, said catch comprising a permanent magnet element adapted to be rigidly mounted on one of said members, a pair of elongated pole pieecs rigidly secured to said magnet element adjacent the poles thereof and extending outwardly from said magnet element with the effective end portions thereof in parallel spaced relation and the end contact faces of said pole pieces being aligned for operative engagement with an armature element, an elongated armature support adapted to be rigidly mounted on the other of said members and to extend at its outer end between said pole pieces when said closure member is in said xed position, an armature element slidably mounted on said support and adapted to engage the aligned contact faces of said pole pieces for holding the closure member in fixed position, and spring means coacting between the outer end of said support and said armature element for retaining the closure member in xed position under spring pressure, the slidable relation between said armature element and said support permitting limited outward movement of said support relative to said armature element in response to movement of said closure member from said fixed positio-n and while said armature element is in magnetic engagement with said pole pieces whereby the inertia of the moving closure member facilitates disruption of said magnetic engagement when said spring means is collapsed.

9. In combination, a heavy door member, a frame member for supporting said door, a powerful permanent magnet unit mounted on one of said members, an elongated armature support mounted on the other of said members and extending rigidly therefrom, an armature element mounted on said support intermediate the ends thereof, said armature element being relatively slidable along the longitudinal axis of said support, said armature element engaging said magnet unit upon said door member being moved to closed position, and spring means coacting with said armature element to oppose the pull of said magnet unit for holding the door member securely in said closed position, said support being suciently long and said spring being suiiciently elastic when said door member is in said closed position to allow substantial but limited relative movement between said armature element and said support before said armature element and said magnet unit separate as said door member is moved from said closed position whereby the inertia of the moving heavy door member facilitates the disruption of the magnetic engagement between said powerful magnet unit and said amature element.

10. In combination, a heavy door member, a frame member for supporting said door, a powerful permanent magnet unit mounted on one of said members, an elongated armature support mounted on the other of said members and extending rigidly therefrom, retainer means on the outermost end of said support, an armature element slidably mounted on said support intermediate the ends thereof, said armature element engaging said magnet unit upon said door member being moved to closed position, and a compression spring surrounding said support and coacting between said retainer means and said armature element to oppose the pull of said magnet for holding the door member securely in said closed position, said spring being only partially collapsed when said door member is in said closed position, and the size of said spring and the length of said support being such that said spring is further collapsible to permit limited relative movement between said armature element and said support before said armature element and said magnet separate as said door member is moved from said closed position whereby the inertia of the moving heavy door facilitates the disruption of the magnetic engagement between said powerful magnet unit and said armature element.

References Cited in the le of this patent UNITED STATES PATENTS 2,252,144 Taylor et al. Aug. 12, 1941 2,693,382 Teetor Nov. 2, 1954 2,719,050 Teetor Sept. 27, 1955 FOREIGN PATENTS 629,903 Great Britain Sept. 30, 1949 631,523 Great Britain Nov. 4, 1949 

